ECT Sensor and Check Engine Light
My son's 2003 Ranger Edge, 3.0L. AT, exhibits the following symptoms:
1. Temp gauge indicates engine is slow to heat, maxes out at 1/3 gauge scale
2. Check Engine light recently illuminated.
3. Autozone OBD reader reports P0125, P0172, and P0174
4. On initial cold startup, after several minutes, there is an audible "click" and radiator top hose begins to heat up.
5. There is only one wire coming out of the ECT sensor and entering a wire harness 8 inches away. The ECT sensor connector has holes for 2 wires.
6. The engine is a recent (1 month ago) replacement with about 60K miles. He has put several hundred problem-free miles on it since the replacement.
7. Weather has recently turned significantly colder.
My thoughts: Research of the OBD codes points to a coolant temp problem, probably the thermostat, less likely the ECT sensor. Based on the codes and other things I've read online, less likely causes include O2 sensor(s), Mass Airflow Sensor, and others.
I was about to change the thermostat on the guess that it is defective, opening at a lower than desired temperature. Based on the "click" I'm hearing, I'm fairly certain it's not stuck open. I was prepping to replace it with a 192 degree thermostat when I noticed the single wire coming from the ECT Sensor and decided to run this by you guys.
My question for you experts: Does anyone know whether there should be a second wire leading from the ECT Sensor? If not, am I on the right track with the thermostat?
Thanks in advance,